Rename wait_irq to yield_toirq.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
diff --git a/src/boot.c b/src/boot.c
index 7676eb7..91663a2 100644
--- a/src/boot.c
+++ b/src/boot.c
@@ -627,7 +627,7 @@
     for (;;) {
         if (retrytime != (u32)-1 && check_timer(end))
             break;
-        wait_irq();
+        yield_toirq();
     }
     printf("Rebooting.\n");
     struct bregs br;